Please see comments below:
From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Friday, September 14, 2007 12:55 AM To: [email protected] Subject: Re: Class II construction question In message <[email protected]>, dated Fri, 14 Sep 2007, "Barker, Neil" <[email protected]> writes: > could a printed wiring track that overheats and fuses under fault >conditions peel off and bridge the gap? Have you ever heard of that happening? I think it's a technological myth. -->I'm not sure what the issue is here since I have joined this discussion late, however I take issue with your statement above. You may think it is a myth but I have seen it many times. Specifically in telephone equipment that was hit by lightning. At times the traces would hang down from the bottom several inches. The resin would be burned away leaving the glass matt without adhesion. It does happen. Fred Townsend >You may want to consider fitting a thin insulating layer between the >underside of your printed wiring board and the base plate. Often done. > >Good luck with the solution. This is why I have a fundamental dislike >of accessible conductive parts on Class II constructions!! But consider that there are hundreds of millions of such consumer electronic products in use, with no incidents being reported. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
